I don't use powder but have friends that like Bobbi Brown..
Do you have oily or dry skin??
I like Guerlain, but it's pricey. For a cheaper option, I like L'Oreal True Match and Maybelline Dream Matte powders. Another good one is Jane Iredale.
Chanel Poudre Universelle Libre!!!
I have Meteorites which adds a little sparkle. On the Nordstrom site, they have a mineral powder in a black case which is very good. You should get the one that best suits your skin tone. The Bronzer is also amazing.
I always felt like powder and foundation aged me...I'm lucky enough to get away with the "freshly scrubbed" look. I try to fix my skin from the inside: poached salmon and blueberries almost every day seems to help a lot!